US 2012/0063187 A1 (JP 2012-65431 A) discloses one example of inverter circuit devices, which includes an output part and temperature sensors. The Inverter circuit device has a U-phase part, a V-phase part and a W-phase part, which correspond to each phase of a motor (U-phase, V-phase and W-phase). Each phase part has a switching element of a high-side arm and a switching element of a low-side arm. The inverter circuit device has a temperature detection circuit (temperature sensor) in an area, which overlaps an area of mounting of one of the high-side arm and the low-side arm.
In the inverter circuit device described above, however, the temperature sensor is located at either one of the high-side arm and the low-side arm of each phase part. The inverter circuit device thus needs the same number of temperature sensors as the number of phase parts and hence costs high.